Implantable medical devices are commonly used today to treat patients suffering from various ailments. Such implantable devices may be utilized to treat conditions such as pain, incontinence, sleep disorders, and movement disorders such as Parkinson's disease and epilepsy, for example. Such therapies also appear promising in the treatment of a variety of psychological, emotional, and other physiological conditions.
One known type of implantable medical device, a neurostimulator, delivers mild electrical impulses to neural tissue using an electrical lead. For example, to treat pain, electrical impulses may be directed to specific sites. Such neurostimulation may result in effective pain relief and a reduction in the use of pain medications and/or repeat surgeries.
Typically, such devices are totally implantable and may be controlled by a physician or a patient through the use of an external programmer. Current systems generally include a primary cell neurostimulator, a lead extension, and a stimulation lead, and two particular applications of systems may be referred to as: (1) spinal cord stimulation; and (2) deep brain stimulation.
A spinal cord stimulator may be implanted in the abdomen, upper buttock, or pectoral region of a patient and may include at least one extension running from the neurostimulator to the lead or leads which are placed somewhere along the spinal cord. Each of the leads (to be discussed in detail hereinafter) often includes from one to sixteen, or more electrodes. Each extension (likewise to be discussed in detail below hereinafter) is plugged into or connected to the neurostimulator at a proximal end thereof and is coupled to and interfaces with the lead or leads at a distal end of the extension or extensions.
The implanted neurostimulation system is configured to send mild electrical pulses to the spinal cord. These electrical pulses are delivered through the lead or leads to regions near the spinal cord or the nerve selected for stimulation. Each lead includes a small insulated wire coupled to an electrode at the distal end thereof through which the electrical stimulation is delivered. The lead may also include a corresponding number of internal wires to provide separate electrical connection to each electrode such that each electrode may be selectively used to provide stimulation. Connection of the lead to an extension may be accomplished by means of a connector block including, for example, a series or combination of set-screws, ball-seals, etc. The leads are inserted into metal set screw blocks, and metal set screws are manipulated to press the contacts against the blocks to clamp them in place and provide an electrical connection between the lead wires and the blocks.
A deep brain stimulation system includes similar components (i.e. a neurostimulator, at least one extension, and at least one stimulation lead) and may be utilized to provide a variety of different types of electrical stimulation to reduce the occurrence or effects of Parkinson's disease, epileptic seizures, or other undesirable neurological events. In this case, the neurostimulator may be implanted into the pectoral region of the patient. The extension or extensions may extend up through the patient's neck, and the leads/electrodes are implanted in the brain. The leads may interface with the extension just above the ear on both sides of the patient. The distal end of the lead may contain from four to sixteen, or more electrodes and, as was the case previously, the proximal end of the lead may connect to the distal end of the extension and held in place by set screws. The proximal portion of the extension plugs into the connector block of the neurostimulator.
Both of the spinal cord stimulation and deep brain stimulation implanted systems traverse portions of the human body that stretch and relax. To account for this stretching and relaxing, the lead and lead extension can be looped to allow for stretching and relaxing with the human body.